A 65-year-old male presents with a rapid onset fever, chest pain and cough with rusty-yellow sputum. Chest x-ray was done. A Gram stain of a sputum sample contained many polymorphonuclear leukocytes and extracellular gram-positive diplococci. Biochemical reactions revealed the organism was bile soluble, optochin sensitive and fermented inulin. Characteristics of the colonies produced on the culture are given below. Which of the following is the most likely pathogen?